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  • Solar power only

    Hi Guys,
    I have just bought at a sale 3 x (24v 260w) panels.
    My question is what is the minimum battery bank I would need to have to have the panels only running a half hp pump with no backup storage.
    I have a mppt controller and only need the pump to run when the sun is out.
    Cheers Mike

  • #2
    Is the Water Pump rated 120 volts AC ?
    What device will turn the Pump On and Off only when the sun shines ( and the Battery Bank is charged ) ?
    Is the MPPT charge controller rated for a 12 or 24 volt Battery Bank ?

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    • #3
      24v system. Hoping you guys had the answers to the other needs I might have. Got a 24v mppt controller 40A.bwas thinking I could set it to cut off at ? V.
      If you think all this is silly just remember I was born in Melbourne.

      Comment


      • #4
        Originally posted by Aussiemike View Post
        Hi Guys,
        I have just bought at a sale 3 x (24v 260w) panels.
        My question is what is the minimum battery bank I would need to have to have the panels only running a half hp pump with no backup storage.
        I have a mppt controller and only need the pump to run when the sun is out.
        Cheers Mike
        With 780 panel watts and using an MPPT type CC you could get about 60 amps of charging. The smallest battery that you should use would use a C/8 charge rate or about 500Ah.

        Now the question is will that 500Ah battery be able to run your pump every day for the hours you want to run it. Please do not confuse sunlight hours with solar panel hours. A pv panel can generate about 85% of it's name plate wattage between 10 am and 2 pm. Sure it will generate some power before 10am and after 2pm but it may not be enough to run your load. That is why you have the battery.

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        • #5
          He's doing 24V, so I think it would be about 32A.

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          • #6
            Originally posted by sdold View Post
            He's doing 24V, so I think it would be about 32A.
            You are correct. Thanks. Somehow I missed his post about the pump voltage

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            • #7
              Would someone wiser than me tell me if this controller
              epever.jpg

              Can handle 3 of these panels in series
              Sorry image would not load.

              Pmax 260w
              IMP 8.41A
              Vmp 30.90V
              Isc 8.86A
              VOC 38.05v
              Cheers Mike
              BTW its the tracer 24v
              4210A

              Comment


              • #8
                Originally posted by Aussiemike View Post
                Would someone wiser than me tell me if this controller
                epever.jpg

                Can handle 3 of these panels in series
                Sorry image would not load.

                Pmax 260w
                IMP 8.41A
                Vmp 30.90V
                Isc 8.86A
                VOC 38.05v
                Cheers Mike
                BTW its the tracer 24v
                4210A



                That model is a 100 Voc. maximum controller. You will be able to get away with 2 panels in series, but not 3.
                2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                • #9
                  How about parallel?
                  38.05v and 25A?

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                  • #10
                    I did acyually see that but thought I might get away with a little over.
                    If I got another panel the same and did two in series and two in parallel.
                    Would I need another controller?

                    Comment


                    • #11
                      If you got one more panel, and ran 2 series & 2 parallel ( 2S2P ) the 40A controller would just squeak by about at it's max. If they give it an honest rating, and it could handle 40A all day without being stressed, like I know a Classic or Morningstar could, I'd do it. Generally I'd seldom expect to see 4 of those panels produce more than 35A @ 25v, because of heat de-rating and imprecise aim.
                      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                      solar: http://tinyurl.com/LMR-Solar
                      gen: http://tinyurl.com/LMR-Lister

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                      • #12
                        Originally posted by Aussiemike View Post
                        two in series and two in parallel.



                        Just to be clear 2s2p is two strings of two series wired panels. Two in series + two in series.
                        2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                        • #13
                          Merry Xmas all.
                          Am I know ok with this for the above mentioned CC if I add another panel?
                          sol.jpg

                          Comment


                          • #14
                            The wiring is correct, 2s2p. The total power is incorrect being that you appear to be figuring Voc. and Isc. You need to multiply the Vmp, and Imp.which should give you 1040 watts. Also, in the real world you aren't likely to ever see that high of wattage unless you are in a high altitude, cold and sunny location.


                            Oh, and Merry Christmas.
                            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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